<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
  <style>
* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
  font-family: 'Poppins', sans-serif;
}
body {
  display: flex;
  justify-content: center;
  align-items: center;
  min-height: 100vh;
  flex-direction: column;
  gap: 30px;
  background: #1d2b3a;
}
.inputBox {
  position: relative;
  width: 250px;
}
.inputBox input {
  width: 100%;
  padding: 10px;
  border: 1px solid rgba(255, 255, 255, 0.25);
  background: #1d2b3a;
  border-radius: 5px;
  outline: none;
  color: #fff;
}
.inputBox span {
  position: absolute;
  left: 0;
  padding: 10px;
  pointer-events: none;
  font-size: 16px;
  color:rgba(255, 255, 255, 0.25);
  text-transform: uppercase;
  transition: .5s;
}
.inputBox input:valid ~ span, 
.inputBox input:focus ~ span {
  color: #00dfc4;
  transform: translateX(10px) translateY(-7px);
  font-size: 12px;
  padding: 0 10px;
  background: #1d2b3a;
  border-left: 1px solid #00dfc4;
  border-right: 1px solid #00dfc4;
  letter-spacing: 4px;
}
.inputBox:nth-child(2) input:valid ~ span, 
.inputBox:nth-child(2) input:focus ~ span {
  background: #00dfc4;
  color: #1d2b3a;
  border-radius: 2px;
}
  </style>
</head>
<body>
<div class="inputBox">
  <input type="text" required>
  <span>First Name</span>
</div>
<div class="inputBox">
  <input type="text" required>
  <span>Last Name</span>
</div>
</body>
</html>